I have created contexts for Someday Maybe and Waiting For. That aligns with the GTD book method, and also allows you to have actions that are both in a project and Someday Maybe / Waiting For.
I don't use the Action categories of Next Action, Active Planning etc. Whilst it does seem to be a shame not to make use of all of the features in the app, it's not necessary either. I keep it simple and it's easier.
Daily and weekly tasks - I use a separate app called "Checksheet" for these, I like the way that completed tasks can be made to disappear from the list (they are just hidden), and the list appears to get smaller the more you tick off.
Notes - I think the notes section is still crap and haven't used it yet, I use an app called Awesome Note.